Construction method for different-period pouring of concrete inside and outside steel pipe composite column pipe

Abstract

The invention discloses a construction method for different-period pouring of concrete inside and outside a steel pipe composite column pipe, and belongs to the technical field of building construction. According to the construction method, a secondary pouring area filled with solidified soil is reserved at the outer root of a composite column pipe, concrete outside the pipe is poured in a segmented mode, the concrete outside the pipe above the secondary pouring area and concrete inside the pipe are poured in the same period, and after the strength of the concrete inside the pipe reaches the designed value strength for a certain time, the concrete outside the pipe is poured. Then concrete pouring is conducted on the secondary pouring area, in this way, the concrete in the pipe bears part of vertical loads under the restraining effect of the steel pipe, the concrete outside the pipe above the secondary pouring area does not bear the load effect, and the composite column has the mechanical property of different-period pouring; the problem of column body deformation or cracking and the hidden danger of leakage caused by asynchronous shrinkage of concrete inside and outside the pipe can be effectively avoided, the column body quality of the steel pipe composite column is effectively guaranteed, the steel pipe concrete composite column has excellent compression resistance and shock resistance effects, and the construction safety is high.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a construction method for pouring concrete inside and outside a steel pipe composite column at different times. Background Technology

[0002] A steel tube-reinforced concrete column (STRCC) is a composite member consisting of a steel tube-concrete core within the cross-section of a reinforced concrete column. STRCC columns can be categorized by cross-sectional shape into rectangular and circular sections. Common cross-sectional structures include circular tube-circular columns, circular tube-square columns, and square tube-square columns, with circular tube-square columns being the most prevalent. STRCC columns utilize the constraint of the steel tube on the core concrete, placing it under triaxial compression, significantly enhancing its compressive strength and ultimate compressive strain. The core concrete also provides support to the steel tube, preventing or delaying inward buckling and improving its local stability. The outer concrete layer not only increases the cross-sectional dimensions and load-bearing capacity, resulting in a more rational distribution of forces within the cross-section, but also protects the internal steel tube from fire and corrosion, thus improving the column's durability. It is evident that composite columns, through the effective combination of high-strength and high-performance building materials such as steel pipes, reinforcing bars, and concrete, enhance the structural strength, load-bearing capacity, and seismic performance of composite columns. They also exhibit good ductility, while reducing the cross-sectional dimensions of frame structure columns to save space. They can well meet the requirements of stiffness, strength, and seismic resistance for high-rise buildings, reduce the cost of corrosion protection for steel pipes, enhance the fire resistance of steel pipes, and offer high construction convenience. Therefore, they have broad development prospects in modern large-span and complex projects, as well as high-rise and super high-rise projects.

[0003] Currently, there are two construction techniques for steel-concrete composite columns: simultaneous construction and phased construction. Simultaneous construction involves pouring the concrete inside and outside the tube simultaneously. Phased construction involves pouring the concrete inside the tube first, and then pouring the concrete outside after it has reached its design strength for a certain period. In simultaneous construction, both the inner and outer concrete sections bear the vertical load simultaneously, which is distributed according to the axial stiffness of the component. In phased construction, the inner concrete section must bear a portion of the vertical load in advance, and the load from the later-poured outer concrete is then distributed to the inner core and outer concrete sections according to their axial stiffness. Composite columns constructed using phased construction techniques can maximize the compressive bearing capacity of the inner core, thereby improving the cross-sectional bearing capacity of the composite column. Therefore, phased construction is commonly used for steel-concrete composite columns in super high-rise buildings.

[0004] Currently, the main construction methods for different stages of pouring generally include the following three steps: ① Pre-embed anchor bolts, install composite column steel pipes, erect column base formwork, and pour concrete inside the steel pipes to form a steel-concrete composite column; ② Use the steel-concrete composite column as a support for the floor beams, and construct the beam-column structure so that the steel-concrete composite column bears part of the vertical load during construction. When pouring the floor slab concrete, reserve post-pouring holes in the floor slab around the column; ③ When the axial pressure of the steel-concrete composite column reaches 0.3 to 0.6 times the design value of the column's axial pressure, pour concrete outside the steel pipe to form a steel-concrete composite column. Because different pouring stages need to meet the design requirements for the superposition ratio (the ratio of the axial force borne by the core column in advance to the total axial force), the construction progress of the composite column concrete is usually as follows: first, pour the concrete inside the steel pipe on the ground floor, then assemble the steel pipe layer by layer and pour the concrete layer by layer until the concrete inside the steel pipe is poured to multiple layers; then, build the pouring platform layer by layer, and then start pouring the concrete inside and outside the pipe. According to the requirement that the concrete inside the pipe is poured for every 1 layer and the concrete outside the pipe is poured for 3 layers, the concrete inside and outside the pipe is poured at the same time. The above-mentioned conventional non-phase pouring construction steps have the following problems: 1. Structural stability risk: Because the concrete inside and outside the pipe is poured at different times, if the shrinkage of the steel pipe and the concrete is not synchronized, it is easy to cause deformation or cracking of the column, which may lead to structural instability in severe cases; 2. Leakage risk: If the construction joint is not properly treated due to insufficient vibration or inadequate curing, rainwater will seep in, which will cause problems such as steel corrosion and reduced durability; 3. Safety risk of the operating platform: Due to the long time difference between the concrete pouring inside and outside the pipe, the operating platform frame is high when pouring outside the pipe, and the safety risk is high when workers work near the edge.

[0005] In view of this, it is essential to improve and optimize the existing construction process of pouring concrete inside and outside the steel pipe composite column at different times, in order to solve the problems of structural stability risks, leakage hazards and operating platform safety risks in the existing technology. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the present invention aims to provide a construction method for pouring concrete inside and outside the steel pipe composite column at different times. This construction method involves pouring the concrete outside the pipe in sections and pouring the upper part of the concrete outside the pipe and the concrete inside the pipe at the same time. This allows the composite column to meet the mechanical performance design requirements of pouring concrete inside and outside the steel pipe at different times, while also ensuring that the upper part of the concrete outside the pipe does not bear any load. This effectively avoids column deformation, cracking, or leakage, and reduces the construction safety risks of secondary erection of the operating platform.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows: A construction method for composite steel pipe columns with different stages of concrete pouring inside and outside the pipe, comprising the following steps: S1. Hoist the steel pipes, accurately position them, and temporarily fix them by welding. Weld the joints of the steel pipes and inspect the welds. S2. Bind the outer column reinforcement to the upper structural beam and slab reinforcement as a whole. Pass some beam longitudinal reinforcement through the steel pipe according to the reserved hole positions. Weld some beam longitudinal reinforcement to the steel pipe and connect it to the upper ring beam bearing plate. S3. Reserve a secondary pouring area at the root of the pipe. After the steel reinforcement is inspected and approved, fill the secondary pouring area with solidified soil, erect formwork to seal and protect the column base, and compact the solidified soil to make the solidified soil strength ≥2M; erect column formwork. S4. Self-compacting concrete is used to pour concrete into the steel pipe. An acoustic logging tube is placed inside the pipe. After the concrete strength inside the pipe reaches 70% of the design value, the integrity is tested by acoustic wave. After the integrity is confirmed, the concrete outside the pipe is poured. S5. Remove the formwork in the secondary pouring area, clean the solidified soil, roughen it, and set up the formwork. Then pour concrete in the secondary pouring area.

[0008] As a preferred embodiment of the present invention, the specific operation of the steel pipe hoisting in step S1 is as follows: the prefabricated steel pipes in sections are hoisted to the designated position, fixed by an adjustable support device and then assembled. A total station is used for precise measurement and positioning, with a plane position error ≤5mm and a verticality error ≤1 / 3000. After the steel pipes are installed, they are temporarily fixed by welding, and the joints of the steel pipes are welded and the weld seams are inspected.

[0009] In a preferred embodiment of the present invention, the height of the steel pipe in step S2 exceeds the reinforcing bars of the upper structural beam and slab by 130-160cm, preferably 150cm.

[0010] In a preferred embodiment of the present invention, the height of the secondary pouring area in step S3 is 40~80cm, preferably 50cm.

[0011] In a preferred embodiment of the present invention, the solidified soil in step S3 contains 5-10% inorganic solidifying agent, preferably 8%.

[0012] In a preferred embodiment of the present invention, the self-compacting concrete in step S4 has a spread of 600~800mm and a slump of (200~240)±10% mm.

[0013] In a preferred embodiment of the present invention, the concrete in the pipe in step S4 is poured using a high-level drop method, with a drop distance of 3-5m. At the same time as the concrete is dropped, a thick steel bar is used for tamping to ensure that the concrete is filled densely.

[0014] In a preferred embodiment of the present invention, when pouring concrete into the pipe using the high-level drop method in step S4, the discharge port of the hopper is 100-200mm smaller than the inner diameter of the steel pipe to ensure that the air inside the pipe is smoothly discharged when the concrete falls.

[0015] As a preferred embodiment of the present invention, before pouring in step S4, vibrating wire strain gauges are attached to the surface of the reinforcing bars at the junction between the beam-column joint and the composite column, and to the surface of the vertical reinforcing bars in the outer column, so as to facilitate load monitoring after pouring; before step S5, axial compression and eccentric compression monitoring tests are conducted using vibrating wire strain gauges to obtain load-displacement curves, strain distribution, and failure mode data.

[0016] In a preferred embodiment of the present invention, the pouring time between step S5 and step S4 is at least 28 days.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The construction method of this invention involves reserving a secondary pouring area filled with solidified soil at the base of the composite column tube to allow for segmented pouring of the external concrete. The external concrete above the secondary pouring area is poured simultaneously with the internal concrete. After the internal concrete reaches its design strength for a certain period, the secondary pouring area is then poured. In this way, the internal concrete bears part of the vertical load under the constraint of the steel pipe, while the external concrete above the secondary pouring area does not bear any load. This method not only gives the composite column different mechanical properties due to phased pouring but also effectively... This invention avoids column deformation, cracking, and leakage risks caused by asynchronous shrinkage of concrete inside and outside the pipe, effectively ensuring the quality of the steel-concrete composite column and giving it excellent compressive and seismic resistance. Furthermore, this invention optimizes the construction method of pouring concrete inside and outside the pipe at different times through a novel secondary pouring method, effectively shortening the overall construction period of the steel-concrete composite column. Compared with existing technologies that use different pouring times, it eliminates the need for a platform for re-pouring concrete outside the pipe, avoiding the risks of high-altitude operations and ensuring high construction safety. Attached Figure Description

[0018] Figure 1 This is a structural schematic diagram of the steel pipe hoisting process in step S1 of the construction method of the present invention. Figure 2 This is a structural schematic diagram illustrating the completion of step S2, rebar tying, in the construction method of the present invention. Figure 3 This is a schematic diagram of the structure of the solidified soil filling area for the secondary pouring in step S3 of the construction method of the present invention. Figure 4 This is a structural diagram illustrating the completion step S3 of the construction method of the present invention: column formwork erection. Figure 5This is a schematic diagram of the structure for completing step S4 of the construction method of the present invention, which involves pouring concrete inside and outside the pipe. Figure 6 A schematic diagram of the structure for pouring concrete in the secondary pouring area in step S6 of the construction method of the present invention. Figure 7 This is a structural schematic diagram of a steel pipe composite column manufactured according to the construction method of the present invention; Figure 8 This is a diagram illustrating the effect of completing step S1 (steel pipe hoisting) and step S2 (rebar tying) in an embodiment of the present invention. Figure 9 This is an illustration of the effect of filling and sealing the secondary pouring area with solidified soil in step S3 of this invention. Figure 10 This is a diagram illustrating the effect of installing a vibrating wire strain gauge on the surface of a reinforcing bar according to an embodiment of the present invention. Figure 11 This is a rendering of the column formwork erected according to an embodiment of the present invention; Figure 12 This is a diagram illustrating the effect of pouring concrete inside the pipe according to an embodiment of the present invention. Figure 13 This is a rendering of the effect of removing the column formwork and the sealing formwork of the secondary pouring area according to an embodiment of the present invention; Figure 14 This is a diagram showing the effect of pouring concrete in the secondary pouring area according to an embodiment of the present invention. The following are the symbols and their meanings: 1. Steel pipe; 2. Column reinforcement; 3. Structural beam and slab reinforcement; 4. Stabilized soil; 5. Formwork; 6. Self-compacting concrete. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] like Figures 1-9 As shown, the construction method for non-phased pouring of concrete inside and outside the steel pipe composite column provided by the present invention specifically includes the following steps: S1. Using a large tower crane, prefabricated steel pipes 1, each 6-9m in length, are hoisted to the designated location. After being fixed with adjustable support devices, they are assembled on-site. A total station is used for precise measurement and positioning, ensuring a horizontal position error ≤5mm and a verticality error ≤1 / 3000. After installation, steel pipes 1 are temporarily fixed by welding to prevent displacement during subsequent construction. The joints of steel pipes 1 are then welded and the welds are inspected. The hoisted steel pipes 1 are as follows: Figure 1 As shown; S2. The outer column reinforcement 2 is integrally tied to the upper-layer structural beam and slab reinforcement 3. A portion of the beam longitudinal reinforcement passes through the steel pipe 1 according to the pre-drilled holes, while the other portion is welded to the upper ring beam bearing plate of the steel pipe 1. The height of the steel pipe 1 exceeds the height of the upper-layer structural beam and slab reinforcement 3 by 130-160cm to facilitate subsequent pouring procedures. The structure after reinforcement tying is as follows: Figure 2 As shown; S3. A secondary pouring area is reserved at the root of the pipe. The height of the secondary pouring area (i.e., the distance between the root of the composite column and the top of the secondary pouring area) is 40~80cm. This height facilitates subsequent secondary pouring work, and is preferably 50cm. Figure 3 As shown, after the reinforcing steel passes inspection, the secondary pouring area is filled with solidified soil 4 containing 5-10% inorganic curing agent. Formwork 5 is erected to seal and protect the column base. The solidified soil 4 is then compacted to a strength ≥2M to meet the bearing requirements of the upper external concrete. Figure 4 As shown, erect column formwork 5; S4, such as Figure 5 As shown, a high-level drop method is used to pour self-compacting concrete 6 with a spread of 600~800mm and a slump of (200~240)±10%mm into a steel pipe 1. The discharge port of the hopper is 100~200mm smaller than the inner diameter of the steel pipe 1 to ensure that the air in the pipe is smoothly discharged when the concrete falls. The drop distance of the concrete is 3~5m. At the same time as the concrete is dropped, a thick steel bar is used to tamp it to ensure that the concrete is filled and compacted. Before pouring, an acoustic logging tube is left in the pipe. After the strength of the concrete in the pipe reaches 70% of the design value, the integrity is tested by acoustic wave. After the integrity is confirmed, the concrete outside the pipe is poured. S5, such as Figure 6 As shown, at least 28 days after the completion of step S4, the formwork 5 of the secondary pouring area is removed, the solidified soil 4 is cleaned and roughened, and the formwork 5 is then erected again. Concrete is then poured into the secondary pouring area. The specific pouring time for the secondary pouring area depends on the time it takes for the concrete strength inside and outside the pipe to reach the design value. After pouring, once the self-compacting concrete 6 of the secondary pouring area reaches the design strength, the formwork 5 is removed, resulting in the following... Figure 7 The steel pipe 1 is a concrete composite column shown.

[0021] Furthermore, before pouring in step S4, vibrating wire strain gauges can be attached to the surface of the reinforcing bars at the junction of the beam-column joint and the composite column, as well as to the surface of the vertical reinforcing bars in the outer column 2, to facilitate load monitoring after pouring. Before step S5, axial compression and eccentric compression monitoring tests are conducted using vibrating wire strain gauges to obtain load-displacement curves, strain distribution, and failure mode data, establishing a mechanical performance database. By monitoring the load borne by the reinforcing bars, the stress state of the composite column during construction can be understood in real time, ensuring it remains within the design safety range. Simultaneously, monitoring the reinforcing bar load verifies the rationality of the construction process, ensuring that the steel pipe and concrete work together under stress.

[0022] Furthermore, the self-compacting concrete 6 used in step S4 must be designed and trial-mixed according to specifications and design requirements, and its flowability parameters such as slump and spread must be controlled. Additionally, vibration should be avoided as much as possible during the pouring of the self-compacting concrete 6 to prevent segregation.

[0023] Example This example illustrates a renovation project in an industrial park in Tangjia Town, Zhuhai High-tech Zone. The construction process of the steel-concrete composite column in Building No. 1 is as follows: S1. Prefabricated steel pipes, each 7m in length, are hoisted to the designated location using a large tower crane. After being fixed with adjustable support devices, they are assembled on-site. A total station is used for precise measurement and positioning to ensure that the horizontal position error is ≤5mm and the verticality error is ≤1 / 3000. After the steel pipes are installed, they are temporarily fixed by welding to prevent displacement during subsequent construction. Then, the joints of the steel pipes are welded and the welds are inspected. S2. The reinforcing bars of the outer column are integrally tied to the reinforcing bars of the upper-layer structural beams and slabs. A portion of the longitudinal reinforcement of the beams passes through the steel pipes according to pre-drilled holes, while the other portion is welded to the upper ring beam bearing plate of the steel pipes. The height of the steel pipes extends 150cm beyond the reinforcing bars of the upper-layer structural beams and slabs to facilitate subsequent pouring procedures. The structure after the reinforcing bar tying in this embodiment is as follows: Figure 8 As shown; S3. A secondary pouring area is reserved at the root of the pipe. The height of the secondary pouring area (i.e., the distance between the root of the composite column and the top of the secondary pouring area) is 50cm. This height facilitates subsequent secondary pouring work. Figure 9 As shown, after the reinforcing steel passes inspection, the secondary pouring area is filled with solidified soil containing 8% inorganic curing agent. Formwork is erected to seal and protect the column base. The solidified soil is then compacted to a strength ≥2M to meet the bearing requirements of the upper external concrete. Figure 10As shown, vibrating wire strain gauges are attached to the surface of the reinforcing bars at the junction of the beam-column joint and the composite column, as well as to the surface of the vertical reinforcing bars in the outer column, to facilitate load monitoring after pouring. Column formwork is erected, as follows: Figure 11 As shown; S4, such as Figure 12 As shown, a high-level drop method was used to pour self-compacting concrete with a spread of 700 mm and a slump of 220 ± 10% mm into a steel pipe. The discharge port of the hopper was 200 mm smaller than the inner diameter of the steel pipe to ensure that the air inside the pipe was smoothly discharged when the concrete fell. The drop distance of the concrete was 4 m. At the same time as the concrete was dropped, a thick steel bar was used to tamp it to ensure that the concrete was filled and compacted. Before pouring, an acoustic logging tube was left in the pipe. After the strength of the concrete inside the pipe reached 70% of the design value, the integrity was tested by sound wave. After the integrity was confirmed, the concrete outside the pipe was poured. S5. On the 28th day after step S4 is completed, remove the column formwork and the formwork for the secondary pouring area. The resulting column base is as follows: Figure 13 As shown; after cleaning the solidified soil, roughen it and set up formwork, then pour concrete into the secondary pouring area, as follows. Figure 14 As shown. After the concrete in the secondary pouring area reaches the design strength, the formwork can be removed to obtain the steel pipe composite column.

[0024] After the multi-story steel pipe composite column was poured, three steel pipe composite columns were randomly selected at four locations in each of the 1st, 3rd, 7th, and 10th floors to test the stress of the external reinforcing bars. The monitoring frequency was approximately once every 5 days, monitoring the stress changes under the load of each additional floor. The monitoring results showed that as the number of poured floors increased, the stress values ​​of the reinforcing bars varied in different directions, but the stress change trend of the reinforcing bars was consistent, with small increments. The stress changed rapidly in the early stage and tended to stabilize in the later stage. This indicates that the stress trend of the external reinforcing bars in the secondary pouring area was the same, which is equivalent to the same vertical load trend borne by the external concrete. The vertical load borne by the external concrete was small, only 5% of the design value of the external reinforcing bar load. This proves that the construction method of the present invention is effective and feasible, can effectively ensure the overall quality of the steel pipe concrete composite column, and well meet the compressive and seismic resistance requirements of the steel pipe composite column.

[0025] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A construction method for composite steel pipe columns where the concrete inside and outside the pipe is poured at different times, characterized in that: Includes the following steps: S1. Hoist the steel pipes, accurately position them, and temporarily fix them by welding. Weld the joints of the steel pipes and inspect the welds. S2. Bind the outer column reinforcement to the upper structural beam and slab reinforcement as a whole. Pass some beam longitudinal reinforcement through the steel pipe according to the reserved hole positions. Weld some beam longitudinal reinforcement to the steel pipe and connect it to the upper ring beam bearing plate. S3. Reserve a secondary pouring area at the root of the pipe. After the steel reinforcement is inspected and approved, fill the secondary pouring area with solidified soil, erect formwork to seal and protect the column base, and compact the solidified soil to make the solidified soil strength ≥2M; erect column formwork. S4. Self-compacting concrete is used to pour concrete into the steel pipe. An acoustic logging tube is placed inside the pipe. After the concrete strength inside the pipe reaches 70% of the design value, the integrity is tested by acoustic wave. After the integrity is confirmed, the concrete outside the pipe is poured. S5. Remove the formwork in the secondary pouring area, clean the solidified soil, roughen it, and set up the formwork. Then pour concrete in the secondary pouring area.

2. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1, characterized in that: The specific operation of steel pipe hoisting in step S1 is as follows: the prefabricated steel pipes in sections are hoisted to the designated position, fixed by the adjustable support device and then assembled. The total station is used for precise measurement and positioning, with a plane position error ≤5mm and a verticality error ≤1 / 3000. After the steel pipes are installed, they are temporarily fixed by welding. The splices of the steel pipes are welded and the weld seams are inspected.

3. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1, characterized in that: In step S2, the height of the steel pipe exceeds the reinforcing steel bars of the upper structural beam and slab by 130-160 cm.

4. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1, characterized in that: The height of the secondary pouring area in step S3 is 40~80cm.

5. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1 or 4, characterized in that: The solidified soil described in step S3 contains 5-10% inorganic solidifying agent.

6. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1, characterized in that: The self-compacting concrete described in step S4 has a spread of 600~800mm and a slump of (200~240)±10% mm.

7. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1 or 6, characterized in that: In step S4, the concrete inside the pipe is poured using the high-level drop method, with a drop height of 3-5m. At the same time as the concrete is dropped, a thick steel bar is used for tamping to ensure that the concrete is filled densely.

8. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 7, characterized in that: When pouring concrete into the pipe using the high-level drop method in step S4, the discharge port of the hopper is 100-200mm smaller than the inner diameter of the steel pipe to ensure that the air inside the pipe is smoothly discharged when the concrete falls.

9. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1, characterized in that: Before pouring in step S4, the vibrating wire strain gauges are attached to the surface of the reinforcing bars at the junction between the beam-column joint and the composite column, and to the surface of the vertical reinforcing bars in the outer column, so as to facilitate load monitoring after pouring. Before proceeding to step S5, axial compression and eccentric compression monitoring tests are conducted using vibrating wire strain gauges to obtain load-displacement curves, strain distribution, and failure mode data.

10. The construction method for non-phase pouring of concrete inside and outside the composite steel pipe column according to claim 1, characterized in that: The pouring time between step S5 and step S4 shall be at least 28 days.

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